Python: Web Beacons in Pylons

A Web beacon is usually an image tag that refers to a 1x1 clear gif on a remote server. The remote server is able to track that the gif was seen when the browser tries to download it. If you're using Pylons, here's how to implement that beacon in a way that won't be cached:

CLEAR_GIF = 'GIF89a\x01\x00\x01\x00\x91\xff\x00\xff\xff\xff\x00\x00\x00\xff\xff\xff\x00\x00\x00!\xff\x0bADOBE:IR1.0\x02\xde\xed\x00!\xf9\x04\x01\x00\x00\x02\x00,\x00\x00\x00\x00\x01\x00\x01\x00\x00\x02\x02T\x01\x00;'
...
def some_action(self):
    # Do interesting things here...
    response.headers['Content-Type'] = 'image/gif'
    response.headers['Cache-Control'] = 'no-cache'
    response.write(CLEAR_GIF)

Comments

jjinux said…

Hmm, it's truncating the CLEAR_GIF. Click on the comments page and click "Show Original Post". Alternatively, look at the HTML source for the page. Sorry for the inconvenience.

11:45 PM

John said…

I think that the no-cache header is intended as an instruction to caching proxies and not to User Agents/Browsers. For this you should probably be setting the Expires header instead.

4:55 PM

jjinux said…

You may be right.

I did what I did because the book "RESTful Web Services" gave an overview on caching and said to do it that way.

1:08 AM

Drawing Sierpinski's Triangle in Minecraft Using Python

In his keynote at PyCon, Eben Upton, the Executive Director of the Rasberry Pi Foundation, mentioned that not only has Minecraft been ported to the Rasberry Pi, but you can even control it with Python. Since four of my kids are avid Minecraft fans, I figured this might be a good time to teach them to program using Python. So I started yesterday with the goal of programming something cool for Minecraft and then showing it off at the San Francisco Python Meetup in the evening.

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JavaScript: Porting from react-css-modules to babel-plugin-react-css-modules (with Less)

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Get ESLint to pass now that react-css-modules is no longer available.Get babel-plugin-react-css-modules working with Less.Get my Karma tests to at least build.Get the Karma tests to pass.Test things thoroughly.Fight off merge conflicts from the rest of engineering every 10 minutes ;) There were a few things that resulted in difficult code changes. That's what the rest of this blog post is about. I don't think you can fix all of these things ahead of time. Just read through them and keep them in mind as you follow the approach above.…

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